Basic Java Questions and Answers
  • What is "Java"?
    Java is a programming language.  The Java language was released publicly in the 90s.  It is conceived by Sun Microsystems.  One reason for Java's popularity is that it can be used to create applets.   (What is an applet?  See below).  Java is also the name of an island in Indonesia.

  • Are Java and JavaScript the same thing?
    They're not.  Although JavaScript is often erroneously referred as Java, they're two different programming languages.  The name similarity has an interesting historical context (some might say: commercial context).  If you're really interested in this subject, search the web for more information.  

  • What is an "applet"?
    The term "applet" refers to to a Java program contained on a web page.  I.e.:  Applets are Java programs that runs within a web browser.

  • Why can't I run applets?
    There might be several reasons:

    • You don't have a Java plug-in.  See below on where you can obtain one.

    • You have the Java plug-in, but it is not enabled.  Enabling the plug-in is usually done from the browser setting.  Warning: malicious applets can pose security risks.

    • Your computer is on a firewall and it's not allowed to run applets.

    • The Java plug-in is not compatible with the applet.  This commonly happens when a newer plug-in is tying to run older applet or vice-verse.  

  • What is a Java plug-in?
    In the world wide web context, a Java plug-in is a program that enables your browser to run Java applets.  

  • Where can I download the Java plug-in?
    You can download the Java plug-in from Sun's website: click here to go there.  Be sure to read the instruction carefully and decide for yourself if you want it.  Also make sure your browser is supported by the plug-in.

  • All I see is a gray box when trying to run a Java applet.  What is the problem?
    The simple answer is: the applet has failed to run.  The most likely reason is not having a Java plug-in.  Another possibility is that the applet has crashed.


  • I am using Internet Explorer on a Windows XP, why can't I play Java applets?  
    Internet Explorer used to have a Java plug-in, but no longer.  This is a licensing issue between Microsoft and Sun.  More info on this is available on Microsoft's website or click this link.

  • What is "Java Virtual Machine?"
    This term refers to a Java plug-in.  
    Java Virtual Machine = Java plug-in.

  • After I upgraded my browser, I could no longer play Java applets.
    Most newer browsers do not have Java plug-in shipped; or it may only be installed when you choose "full" or "custom" installation.  Check the documentation on the browser.  Alternatively, you can download the Java plug-in from Sun's website: click here to go there.  Be sure to read the instruction carefully and decide for yourself if you want it. 
    Warning: malicious applets can pose security risks.

  • How do I know if I have a Java plug-in or not?
    If you can run a Java applet, then you have a Java plug-in.  I know that isn't terribly clear.  There are other ways, depending on what plug-in you have.  For example for Sun's Java plug-in in Windows, you usually will have a "Java Plug-In" item in the Control Panel after it's installed.  You can click on the Java Plug-In icon to see the setting and test the plug in.

  • I'm getting "Parameter error" or "Missing parameter" message when running the applet.
    If you ever encounter this message on one of the applets on this site, please e-mail me.

 (C) F. Permadi